Which 7mm cartridge?

I am in the planning stage for a new 7mm LR build. What cartridges do you like for 7mm bullets? Current thinking is to use a Bighorn Long Action and most likely a 26 inch barrel. Sierra makes a 183 grain SMK that has a G7 BC of .377 which looks promising. I am thinking 7mm Rem Mag or ???

 

I am building a 284 Winchester because it seems to be a pretty efficient cartridge with more inherent accuracy than other 7mm chamberings.

The downside is muzzle velocity with 180-ish grain bullets is going to max out around 2,900 with an accuracy node around 2,800, it will remain supersonic at the mile depending on elevation but it's not going to have the legs of a cartridge that starts with 3,100 fps at the muzzle (with the same bullet).

I'm going to try 2,000+ yard shooting but only because that's what the closest ELR event has. Otherwise it's going to be 100 yards for break in and basic load development and 1,000 yards at the range I go to most frequently.

 

I just built a straight 284 and couldn't be happier...but that's the only experience I have with the 7mm platform...

 

I'm shooting 7mm rsaum, very accurate with 162, 180, ELD-M and 180 Bergers. Very easy to tune with H1000. Others are really liking the 7mm Sherman Short Mag. As mentioned the 284 is a great round! Depends on distance, hunting, target, etc.

 

I built my mountain rifle chambered for the 7 SAUM, very happy I did.
Steve Bair

 

7 SAUM is my vote. More powder efficient than a 7 rem mag and has more power than the 284 for hunting. Case design better too. There's brass available for this cartridge as well now from several companies. I got mine from Gunwerks. If you have a standard bolt face, then go 284 I guess. Those are my 2 picks.

 

I'd probably do a 7mm-300wsm throated long for the 180s or 195gr.
Being the velocity hog that I am, I love my 28 Nosler, fully aware of barrel life potential. I'm only loading 175 Bergers with RL33 at 3320 ( hunting rig).
I wouldn't feel like I was wasting a perfectly good long action on a short action cartridge.

 

Is anyone else using Gunwerks 7SAUM Brass, how is the quality?

 

The nice thing about 284 is you can make brass from Lapua 6.5-284 brass, buy 284 brass from Peterson or Norma, three high quality options.

Other 7mm cartridges are a lot harder to find good consistent brass.

 

7-300 WSM or 7RUM

 

7mm Blaser Mag. I'm shooting 180gr Bergers w/68.5gr RL26 from a Hart #4 finished at 26in. and that gives me 3088-3100fps.

 

How do you like that 7 Blaser? Seems about the same capacity as 7mm RM, kind of between 7wsm and 28 Nosler. What make brass are you loading ?

 

It's been great, very easy to load for. My particular build isn't all that heavy with its fluted #4 and running it with a brake it's very soft shooting, even with the 180's.

The brass is made for Blaser by Norma and is pretty easy to get through a few different online vendors, I think I bought my brass from MidSouth Shooters Supply and Redding makes dies for the 7mm Blaser Mag.

Case capacity is nearly the same as the 7 Rem mag with the 7 Blaser only being a tiny bit larger. My fired cases measure right at 84.5gr of water. The Blaser case is shorter but fatter than a 7 Rem mag and unlike the 7 Rem they aren't a belted case. The Blaser case has a fairly long neck on them but since the overall case length isn't very long, even with the longest heaviest bullets you have plenty of room in a long action. My OAL with the 180 Bergers is only 3.260 and that's at 10 thou off touch.

 

It's basically an intermediate length WSM cartridge:

 

Another vote for the 7mm SAUM.

 

If the 7mm Rem mag and 7 WSM ever hooked up and had a love child, the 7mm Blaser Mag is what you'd get.

 

Let me know what barrel life is like with this cartridge and RL26...it has eaten a few barrels up of mine in 270wsm and 6AI.

 

I'll never use up the barrel in this one, it's not a high volume gun for me. There's a few guys over on the LRH forum shooting the 7mm Blaser and one or two that have 7mm Blaser Improved versions as well.

I once thought a necked down 270-7mm Blaser shooting the Berger 170's would be pretty cool but I kinda got off that idea and moved on to a different build.

 

I had a 27N at PacNor when they burned. I have about 3000 170gr Bergers just sitting there doing nothing. (I invested in buying Bullets.com out of stuff)

Might have to see about getting a 277 Blaser reamer.

 

The Blaser case, IMO, is a great size for running a 26in barrel. I think when you get into some of the more overbore cartridges, like the 28 Nosler or 7 RUM, they need more barrel length so they can take advantage of all that powder. In a 26in tube, cartridges like the 7mm Blaser can run right there with the much larger cases and do so with 15+ grains less powder. Put a 30 inch tube on them and it's a different story, horsepower easily wins the race.